This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The purpose of the study is to analyze the telomere (ends of a chromosome) length in various blood cells from normal healthy baboons in relation to their age. We have found in normal humans that the telomere length in various blood cells clearly declines with age. This finding suggests that the telomere length can be used as a surrogate marker for biological age. We would like to know if the same applies to other large outbred animals such as baboons. An additional rationale for the study is that by inclusion of animals with a detailed pedigree and genetic map we hope to link variation in telomere length with specific genetic loci.